Giali is the largest of the satellite islands of Nisyros, and one of the most productive quarries of pumice in the world. Its particularly fine and homogeneous deposits of pumice, reaching depths of almost 180m, have been exploited to the point of substantially altering the profile of the island. The strata in the cliffs created in this process are of particular interest to the vulcanologist seeking to understand the sequences of eruptions, as well as to the paleontologist for the fossilised or vulcanised remains of crustaceans and seeds which have been preserved in them. The pumice itself is used today in a range of abrasive household cleaning fluids sold all over the world. Recent excavations on the island have brought to light remains of many houses from the period of Ottoman occupation—evidence of an intensive pre-industrial exploitation of the material.
Like Milos, Giali also has perlite deposits in the north of the island and obsidian in the northwest corner. The obsidian from Giali is distinguishable by its slightly spotted appearance as opposed to the darker, purer variety from Milos. The presence of these materials has meant that the island has been inhabited since earliest times: a significant Late Neolithic settlement, with dwellings (including a building of elliptical plan) and workshops, has been uncovered near the summit of the southwest part of the island: crucibles for smelting copper have also been found. There is less visible evidence of a Bronze Age presence even though it is clear there was a Minoan interest in the island’s obsidian. The reported remains of an Hellenistic ‘nymphaeum’ is congruent with the fact that the island surprisingly possesses many freshwater wells. Pliny refers to the island as ‘Cisirusa’; but it also bears the mediaeval name ‘Istros’, and is called ‘Verialis’ in the 17th cen tury, from which comes its modern name ‘Giali(s)’. The island’s resident population of 30 is supported wholly by its extraction industry. The west of the island is covered in a scrub of pine, arbutus and some olive; the southern peninsula boasts several of the best beaches to be found in this group of islands. These are visitable by excursion boat from Mandraki in the summer season.
Giali Island is part of the Dodecanese Island Group, Greece.